This proposal is to determine the relative contributions of moderate weight reduction and moderate sodium restriction to the achievement of clinically significant reductions of blood pressure among subjects with borderline hypertension. One-hundred moderately overweight men with borderline hypertension meeting inclusion criteria will sequentially enter two intervention periods following one month baseline control period: 1. Moderate weight reduction of 5 to 10 kilograms through caloric restriction with sodium intake maintained at 150 mEq per day. 2. Weight maintenance plus dietary sodium restriction to 70 mEq sodium per day. Follow up observations will be made during the five-month intervention period with colaric and sodium intake assessed by body weight, skinfold thickness and 24-hour urine collection and these related to random zero clinic blood pressure measurements. The cardiovascular effects of weight reduction without reduction in sodium intake will be investigated in a subgroup of 20 patients from the weight group. This research would help establish the magnitude of the relative contribution of weight reduction per se and sodium restriction to the change in blood pressure associated with weight loss, the mechanisms of blood pressure lowering associated with weight loss, and the role of the moderately sodium restricted moderate weight reduction diet in the management of borderline hypertension. In addition, it would move the field a step closer to addressing the ultimate question of primary prevention of essential hypertension.